The present invention relates a synthetic compound which serves as an antigen for recognition by a monoclonal antibody to advanced glycosylation endproducts.
It has been discovered that the protein glycosylation and the resultant formation of crosslinks leads to what has become known as advanced glycosylation (glycation) endproducts and cross-links. The nonenzymatic reaction between glucose and the free amino groups on proteins to form a stable, 1-deoxyketosyl adduct, known as the Amadori product, has been shown to occur with hemoglobin, wherein a rearrangement of the amino terminal of the beta-chain of hemoglobin by reaction with glucose, forms the adduct known as hemoglobin A.sub.1c. The reaction has also been found to occur with a variety of other body proteins, such as lens crystallins, collagen and nerve proteins. See Bucala et al., "Advanced Glycosylation; Chemistry, Biology, and Implications for Diabetes and Aging" in Advances in Pharmacology, 23, pp. 1-34, Academic Press (1992).
Moreover, brown pigments with spectral and fluorescent properties similar to those of late-stage Maillard products have also been observed in vivo in association with several long-lived proteins, such as lens proteins and collagen from aged individuals. An age-related linear increase in pigment was observed in human dura collagen between the ages of 20 to 90 years. Interestingly, the aging of collagen can be mimicked in vitro by the cross-linking induced by glucose; and the capture of other proteins and the formation of adducts by collagen, also noted, is theorized to occur by a cross-linking reaction, and is believed to account for the observed accumulation of albumin and antibodies in kidney basement membrane.
In U.S. Pat. No. 4,758,583, a method and associated agents were disclosed that served to inhibit the formation of advanced glycosylation endproducts by reacting with an early glycosylation product that results from the original reaction between the target protein and glucose. Accordingly, inhibition was postulated to take place as the reaction between the inhibitor and the early glycosylation product appeared to interrupt the subsequent reaction of the glycosylated protein with additional protein material to form the cross-linked late-stage product. One of the agents identified as an inhibitor was aminoguanidine, and the results of further testing have borne out its efficacy in this regard.
To fully elucidate the mechanism of the formation of advanced glycosylation endproducts, and as a means of monitoring the onset and progress of diseases which occur as a result thereof, both polyclonal and monoclonal antibodies have been developed. In the course of developing these antibodies, it has been necessary to identify and characterize antigens which are recognized thereby. During the isolation and development of the antibodies of co-pending U.S. Ser. No. 08/367,507, filed Dec. 28, 1994, the antigen of the present invention was isolated and characterized.